Lubricating oil additive compatibility improver



LUBRICATING 01L ADDITIVE COMPATIBILITY IMPROVER Adlai E. Michaels, Cranford, and Niilo v. Hal-rala, Westfield, N.J., assignors to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Application October 24, 1955 Serial No. 542,488

Claims. (Cl. 252-33.4)

This invention relates to methods of preparing improved lubricating oil compositions containing different additives having some degree of incompatibility. More particularly, it relates to methods of improving the compatibility of metallo-organic additives and polymeric additive materials in lubricating oil compositions. It relates also to lubricating compositions containing different additive materials exhibiting some degree of incompatibility to which have been added compounds which will be desig nated compatibility improvers.

Lubricating oils manufactured by conventional methods are often unsuited for use under conditions encountered in internal combustion engines and for diverse industrial purposes. Satisfactory lubricating can be generally given by almost any type of lubricant of the proper viscosity for brief periods of time. However, for a sustained service under normal operating conditions the quality of lubricants becomes important and it is necessary for the lubricant not only to carry out the primary functions but also to exhibit the following advantages: (1) the lubricant should operate satisfactorily over a wide temperature range, and (2) the deleterious effects of excessive engine deposits should be countered. In order to achieve these performance objectives, important characteristics of lubricating oils must be enhanced, especially viscosity, viscosity index, pour point and ability to remove carbonaceous deposits. To obtain these and other desirable results, various additive materials have been blended with lubricating oils to extend the quality of lubricants for specific purposes beyond the level which can be reached by known manufacturing methods.

Generally, additives have been developed for specific purposes, for example, pour point depressants, viscosity indeximprovers, sludge dispersers, detergents, and the like. To obtain a general purpose lubricant having a high level of performance with respect to pour point, viscosity index, sludge dispersion, and the like, it is necessary to incorporate in the lubricating oil base stock many varied additive materials. Because, of the diverse nature of many of these materials, it is not surprising that a certain incompatibility among them exists. For example, metallo-organic compounds used as detergent additives are frequently incompatible with high molecular weight polymeric materialsused primarily as thickeners, viscosity index improvers, pour point depressors, etc. Lubricating oils having incorporated therein the above-mentioned additive materials are frequently unacceptable because of turbidity or because of viscosity instability, etc. It has also been found that certain of the metallo-organic additive materials actually reduce the effectiveness of certain of the polymeric addition agents. For instance it has been found that the pour point depressing potency of some of the additive materials is markedly reduced when blended with a metalloorganic sludge dispersing agent in an oil base.

It has now been discovered that the addition of certain oxygenated organic compounds of the glycol ether type improves the compatibility of metallo-organic addi- 2,935,284 Patented May 10, 1060 tives and highly polymeric additives, and corrects thereby the unacceptable turbidity or viscosity increase of a lubricant using the two additives. It has also been found that the undesirable depreciation of pour point depressing potency is removed by the incorporation into the blend of these oxygenated organic compounds.

These oxygenated organic compounds may be represented by the formula:

where R is an alkyl group having 1 to 8 carbon atoms, R' is hydrogen or an alkyl group having 1 to 8 carbon atoms, and n is an integer from 1 to 8.

Among the operable oxygenated compounds covered by the formulaabove are the following:

Ethylene glycol mono-methyl ether Ethylene glycol mono-ethyl ether Ethylene glycol mono-butyl ether Diethylene glycol mono-methyl ether Diethylene glycol mono-ethyl ether Diethylene glycol mono-butyl ether Triethylene glycol mono-methyl ether Triethylene glycol mono-ethyl ether Tetraethylene glycol di-methyl ether Polypropylene glycol monoalkyl ethers Polypropylene glycol di-alkyl ethers Oxygenated organic compounds of the class enumerated may be dissolved in oil mixtures or solutions which contain incompatible additive materials for the purpose of minimizing or eliminating said incompatibility. These oxygenated compounds may be added (1) to the base oil before the addition of the polymeric additive or the metallo-organic additive, (2) to the oil blend after the addition of either the. polymeric additive or the metalloorganic additive, (3) to the oil blend after the addition of the polymeric additive and the metallo-organic additive, and (4) to the metallo-organic additive.

The oxygenated organic compounds are ordinarily used in amounts varying between about 0.0l% to 5.0% by weight, preferably 0.05% to 3.0% by weight.

The polymeric additive materials which have utility as viscosity index improvers and pour point depressants and which are found to be incompatible to some degree with the metallo-organic detergent inhibitors are the polymerized or copolymerized esters having ester chain lengths within a range of from 8 to 18 carbon atoms in a substantially straight chain. These additive materials are covered by the term alpha,beta-unsaturated carboxylic acid ester polymers or copolymers. They include, among others, polymers and copolymers of esters of acrylic, methacrylic, crotonic and isocrotonic acid, esters of the dibasic acids, such as, maleic, fumaric, citraconic and mesaconic acid, copolymers of these acid esters with vinyl esters such as vinyl acetate, vinyl propionate, vinyl 'butyrate, vinyl caproate, vinyl Ilaurate, and the like.

The preparation of these additive materials is accomplished by straight forward methods and present no problem to the art. Examples of the preparation of representative types are set out below:

PREPARATION OF DI-ALKYL MALEATE ESTER A 3-liter flask equipped with a Water trap and a reflux condenser was washed with 294 g. of maleic anhydride, 1118 g. of the alcohol obtained by hydrogenation of coconut oil and containing an average of 13.5 carbon atoms per molecule, 2 g. of sulfosalicylic acid, 400 cc. of xylene, and 200 cc. of naphtha. The above mixture was refluxed for a total of 14 hours, during which time 58 cc. of water were collected. The reaction product was diluted with about 1,000 cc. of benzol and then given four washes with to sodium carbonate solution and two with water. The solvents were removed by evaporation on a steam bath. The resulting maleate ester had a saponification number of 230, a neutralization number of 0.5, and a viscosity at 210 F. of 41.7 SUS and an average molecular weight of about 495.

COPOLYMERIZATION OF VINYL ACETATE WIIH MALEATE ESTER A l-liter 3-necked flask equipped with a condenser, stirrer, and a thermometer was charged with 200 g. of a lubricating oil having a viscosity at 210 F. of 44 SUS and 300 g. of the maleateester as prepared above. This mixture was heated to about 30 C. after which it was blown with nitrogen for about 5 minutes. There was then added 4 g. of benzoyl peroxide and the mixture was again blown with nitrogen for about 5 minutes. Vinyl acetate addition was started withstirring about 45 minutes after the addition of the benzoyl peroxide and a total of 100 g. of vinyl acetate was added during the course of 1% hours. The reaction mixture was maintained at 80 C. with stirring for 20 hours'from the first addition of the vinyl acetate. The resulting copolymer had a viscosity at 210 F. of 3042 SUS.

PREPARATION OF DI-ALKYL FUMARATE-VINYL ACETATE COPOLYMER 650 g. coconut alcohol fumarate (1.31 mols) 113 g. vinyl acetate (1.31 mols) 85 cc. n-heptane 7.63 g. 60-mesh benzoyl peroxide The above charge was stirred for 17 hours 10 minutes at 70 C. under nitrogen atmosphere, n-Heptane and unreacted vinyl acetate were removed by evaporation at 80 C. under vacuum. The resulting copolymer product which was water-white and highly viscous had a molecular weight of about 7,100 Staudinger.

PREPARATION on POLYMERIZED ACRYLATE AND METHACRYLATE ESTERS The esters of acrylic and methacrylic acid are simply prepared by an ester interchange reaction using the desired alcohol, a C -C alcohol, and the methyl esters of the acids. Usually an acidic catalyst is used to promote the interchange. Polymers of the esters are prepared r by heating the esters to a temperature for about hours at about 100 C. in the presence of a small amount of benzoyl peroxide catalyst. Any unreacted ester may be removed by heating the product in a vacuum (0.5-1 mm. Hg) to a temperature just about the boiling point of the ester. The polymers obtained are usually colorless or faintly yellow.

The polymeric additive materials having viscosity index improving or pour z'point depressing properties. are blended into lubricating oils in amounts between about 0.02% to 10% by'weight, preferably 0.1% to 5.0%, percentages being by weight, based on the weight of the total composition.

The metallo-organic additive material having the desirable detergency-improving characteristics are preferably the metal salts of sulfonic acids, either natural or synthetic, metal salts of alkylated phenols, metal salts of sulfided alkyl phenol, or the reaction products ofthe metal salts of sulfided alkyl phenols and phosphorus sul fide. With these materials may be combined minor d amounts of other known additives, such as metal salts of compounds containing both sulfur and phosphorus, sulfurized hydrocarbons, and the like. The barium salt of the alkyl phenol sulfide is particularly useful either alone or reacted with phosphorus sulfide. Calcium sulfonate is an especially preferred sulfonate. These materials are well known in the art of their preparation and are described in detail in the literature. It has been found thatoil compositions containing from 0.2%-:to 3.0% by weight of these detergent inhibitors, based on the weight of the total composition, have desirable detergentproperties. A. preferred range is from 0.8% to 2% by weight.

' As is set out in detail above, the oil compositions of this invention comprise mineral lubricating oils containing combined therein (1) a copolymer material which imparts. desirable properties of viscosity indeximproving and/or pour depression to the blend, (2) a metallo organic additive which is useful for improving the detergency characteristic of the oil blend, and (3) a compatibility improver which serves to minimize or eliminate any turbidity or instability caused by a mixture of the rnetallo-organic additive and the copolymeric material,

' in any way.

In order to more explicitly define the invention outlined above, the following examples are given, it being understood that these examples are only illustrative of the. inventiveconcept and not considered to be limiting Example I A solvent extracted Mid-Continentparafiinic oil hav-. ing a Saybolt viscosity of 46 seconds at 210 F. and a 'viscosity index of had added thereto 0.2% of an alkyl maleatevinyl acetate copolymer prepared accord ing to the technique outlined above. Ten separate samples of the above lubricating oil composition were set aside. To five of these samples were added 0.8% of five separate samples of inhibitor-detergents consisting of the barium salt of alkyl phenol sulfide reacted with phosphorus sulfide. All five blends were hazy or turbid initially, and on several days standing, all blends were very turbid with a precipitate settling out in one blend. To the remaining five samples were added the same inhibitor-detergent additives but in this case the inhibitor detergent additives contained diethylene glycol mono-v ethyl ether (sufficient quantities to give a concentration of 0.02% in the final blend). After standing two and a half months, the latter samples were found to be perfectly clear.

' Example 11 Two samples were prepared as in Example I with the exception that a different alkyl dibasic acid ester-vinyl acetate copolymer was employed. The blend without the compatibility improver turned cloudy immediately, but the blend containing the diethylene glycol mono-ethyl ether (0.02% in final blend) was still clear at the end of the two and a half months examination period.

Example -III Example I V Example III was repeated except that a dilferent sample of alkyl dibasic acide ester-vinyl ester copolymer was employed and 0.02% instead of 0.04% compatibility improver was employed. Results were identical with those observed in Example 1H.

Example IX Two blends were prepared using the same base stools,

same polyester copolymer and same detergent additive described in Example VIH. To one of the blends was added 0.04% dimethoxytetraethylene glycol. The blend without the compatibility improver was cloudy initially whereas the latter blend was clear initially but showed a slight haze at the end of a.40-day low temperature F.) storage test.

r The results of the above experiments may be summa rized as follows: i

TABLE I.-COMPATIBILITY OF POLYESTER COPOLYMERS WITH METALLO-ORGANIC ADDITIVES Blends contain 0.2% copolymer in extracted Mid-Continent oil having a Saybolt viscosity of 46 seconds at 210 F. and a viscosity index of110.]

Appearance of Blend (Without Appearance of Blend Detergent Additive Compatibility Improver) Compatibility Improver Containing Compatibllity Improver 0.8% Metal salt of alkyl phenol sulfide-l-phosphorus Turbid initially; precipitate on 0.02% Diethylene glycol mono- Clear end of 2 sulfide. stan tug. ethyl ether. months. 0.8% Metal salt of alkyl phenol sulfide+phosphorus Haze initially; very turbid in do All clear end of 2% sulfide (4 samples). several days. months. 1.0% Metal salt of alkyl phenol sulfide Slight haze In one week 0.005151%1 lglilethylene glycol mono- Do.

e y 0 er. 0.8% Metal salt of alkyl phenol sulfide Slight haze in several days; do Clear end of 2% cloudy2 wks. months. 2.0% Metal salt of alkyl phenol sulfide+phosphorus Slight haze initially 0.025% Diethylene glycol mono- All clear end of 2% sulfide+calcium mahogany soap (4 samples). eth ether. months. 0.8% Metal salt of alkyl phenol sulfide+phosphorus Turbidinltially; very turbid on 0.04% Methoxy triglycol Clear end oizl sulfide. standing. months. o do 0.02% Methoxy triglycol 1 Do.

Do d 0.04% I Dimethoxytetra-ethylene Clear initially.

yco Do Cloudy initially 0.02% Diethylene glycol mono- Clear end of 2% ethyl ether. months. Do. n 0.04% Diethylene glycol mono lDo.

ethyl ether. Do 0.02% Diethylene glycol mono- Do.

ethyl ether.

- Compatibility improver added directly to oil blend. I Slight haze at end of 40-day low temperature (40 F.) storage test.

latter blends were clear after two and a half months" standing.

Example VI Example. VII

Two oil blends were prepared using the same test oil and the same polyester copolymer (0.2%) described in Example I. To one blend was added 0.8% of calcium isootcyl phenol sulfide and to the second blend was added 0.8% of the same additive containing diethylene glycol mono-ethyl ether (0.006% concentration in final blend). The first blend exhibited a haze in several days and was cloudy in 2 weeks whereas the blend containing the compatibility improver was clear at the end of two and a half months.

Example VIII Three oil blends composed of 0.2% alkyl dibasic acid ester-vinyl acetate copolymer and the same basestock described in Example I were prepared. To one blend was added 0.8% of P 8 treated barium isooctyl phenol sulfide, to the second blend was added 0.04% methoxy triglycol and 0.8% of the same detergent additive and to the third blend was added 0.8% of the same detergent additive which contained methoxy triglycol (0.02% concentration in final blend). The first blend was cloudy immediately while the two blends containing the compatibility improver were clear at the end of two 'and a half months.

An examination of the data appearing in the table above points out the efl'icacy of the compatibility improver of this invention. In all instances, the initial turbidity was removed by the addition of minor amounts of the.

Example X Using as a lubricating oil base a highly refined Mid- Continent distillate of SAE 20 grade there was prepared a composition containing 0.02 wt. percent of a copolymer of Lorol B fumarate and 20% vinyl acetate prepared as described above. The ASTM pour point of the blend was -25 F. To enhance the detergent inhibiting properties of this blend there was added 5% by weight of a blend of calcium cetyl phenate which contained a small amount of sulfurized paralfin and a minor amount of zinc dialkyldithiophosphate. The pour point of the resulting composition Was increased 30 to +5 F. This composition was entirely unsuited for low temperature use. The second composition was prepared containing identical amounts of polymeric additive and the detergentinhibitor and in addition 0.05% by weight of diethylene glycol mono ethyl ether. The ASTM pour point of this blend was 25 F. clearlyshowing the utility, of the oxygenated organic compound.

Example XI absence percent of the:detergent--inhibitor described in- Example X above had an ASTM: of .-10 A second blend.

8 What is claimed is:

, 1. A non-turbid -.lubrieating oilblend whichconsists essentially of a" minera-lzoil basestoclc havingcombined. therein about 0.05% to about-10% by weight of.a-.viscos--:

containing" identical amounts-of the'poly'merized. methity index improving material'selected from the classcon a'crlylate ester and the detergent-inhibitor." in: the same sisting' of polymerized alphabetwunsaturated carboxylic base stock was. preparedand in: addition 0.05 by: acid esters containing from about 8 to about 18 carbon weight of a diethylene glycol mono-ethyl. ether was. atoms in the ester portion thereof and copolymers of added. The ASTM pour point ofthi'sifina'l composisuchesterswwith vinyl esters, from about 0.2% to.3.0% tion was 30 F., pointing out that in this instance,'like by weight of a' dete'rgentinhibitorselected from the class; in Example X above, the depreciation of-.the pour point consisting of metallic salts of. sulfonic acids and from; depressing potency of the polymerized methacrylate ester 0.01% to 5.0% of a material having the formula by the detergent inhibitor" was removed. 7 RO(CH2CH2O)nR,

- Example '15 wherein R is an alkyl group containing from 1 to 8'car-' To show the viscosity stabilizing effect of the cornbon atoms, R. is a radical selected from the group conpatibility' improvers on various blends containing both sisting of hydrogen and alkyl groups containing from 1 detergent inhibitors oi the alkylated phenol-sulfide andto8 carbon atoms and n is an integer from 1 to 8. I petroleum sulfonate typeand viscosity index improvers, 2. A. non -turbidlubricating oilblend which consists; twelve blends were made and submitted to storage, staessentiallyof a mineral oil base stock having combined bility tests. The blends were prepared by admixing the therein about 0.05% to about 10% by weight of a cocomponents, heating to about 150 F. forv 15 minutes with polymerof a dibasic acid ester containing from 8 to 18 stirring. Data are set out in the table below. carbon atoms in the ester. portion thereof and a vinyl TABLE Ir Blond 1 2 3 4 5 e 7 s' 9 10 11 121 Composition (Vol. Percent):

ase Oil 1 Polymethacrylate Calcium Sulfonate (la-Ba Salt of Diisobutyl Phenol Sulfide Zn Dialkyl Dithiophosphate-L. Piss-treated Terpene Compatibility Improver 4 Test Results:

Viscosity SUSI100 F.)

0i Original Blend Viscogiltly Change After Storage of- 1 A solvent extracted Mid-Continent neutral, viscosity 210 F. of 100 SUS in Ex. 1 and 2; in Ex. 812, an SAE 10W-30 base oil, Mid-Continent (Acryloid 763.)

solvent extracted.

2 A polymerized methacrylate ester containing 0 0 in the ester groups.

3 The alkyl groups correspond to the alkyl groups of methyl-isobutyl carblnol.

4 Diethylene glycol mono-ethyl ether.

The data in the table above shows the eifect of inclusion of the compatibility improvers of this invention in blends containing. various additive materials. It is seen that the viscosity stability of theblends are greatly enhanced by the compatibility improver.

To summarize briefly, this invention relates to an oil composition which consists essentially of a mineral lubricating oil, from 0.5% to 10% of a polymerized a1pha,beta=unsaturated carboxylic acid. ester containing from 8 to 18 carbon atoms in the ester portion thereof and copolymers of. such esters with vinyl esters, from 0.2 to 3.0% of a metallic salt of a petroleum sulfonic acid, a metal salt of an alkylated phenol, a metallic salt of a sulfided alkylated phenol, or the phosphorus sulfide reaction product of such metallic salts, and from 0.01 to 5.0% of a compatibility improver havingv the formula:

RO(CH CH O),,R wherein R is an alkyl group containing from 1 to 8 carbon atoms, R is hydrogen or an alkyl group containing from 1 to 8 carbon atoms,'and n is an integer from 1 to 8.

'The preferred embodiment contemplates the use of a copolymer of a dibasic acid ester containing from 10 to 16 carbon atoms in the ester portion thereof, with a vinyl ester, the barium salt of an alkylated phenol sulfide, and a diethylene glycol ether.

This is a continuation-in-part of application Serial No. 285,531, filed May 1, 1952, for the same inventors, and now abandoned, which in turn is a continuation-in-part of. application Serial No. 214,652, filed March 8, 1951, now-Us. Patent 2,602,048.

ester, from about 0.2% to 3.0% by weight of a deterge'n inhibitor selected from the class consisting of metal salts ofisulfonic acids, and from about 0.05 to 3.0% by weight of a' compatibility improver having the formula R0(CH CH O),,R' wherein R is an alkyl group containing from 1 to 8 carbon atoms, R isv a radical selected from the group consisting of hydrogen'and alkyl groups containing from 1v to 8 carbon atoms, and n is an integer from 1 to 8.

3. A non-turbid lubricating oil blend which consists; essentially of a mineral oil base stock having combined therein about 0.1% to about 2.0% :by weight of a copolyemer of a fuma'rate ester containing from 8 to 18 carbon atoms in the ester portion thereof and a vinylester, from:

about .08% to 2.0% by weight of a detergent inhibitor selected from the class consistingof metal salts of 8111-1: ionic acids, and from about 0.05% to 4.0% by weight of a compatibility improver of the formula 4 RO(CH CH O),,R' wherein R is an alkyl group containing from 1 to 8 carbon atoms, R is a radical selected from the group con? sisting of hydrogen and alkyl groups containingfrom. l to 8 carbon atoms, and n is an integer from 1 to 8.

4. A lubricating oil blend according to claim 1 wherein said detergent inhibitor is calcium sulfonate.

5. A lubricating oil blend according to claim 1 wherein said compatibility improver is diethylene glycol monoethyl ether.

6. A lubricating oil blend according to claim 2 wliierein the detergent inhibitor is calcium sulfonate.

7. A lubricating oil blend according to claim 2 wherein said compatibility improver is methoxy triglycol.

8. A lubricating oil blend according to claim 2 wherein said compatibility improver is dimethoxy tetraethylene glycol.

9. A non-turbid lubricating oil blend which consists essentially of a mineral oil base stock having combined therein about 0.1% to about 2.0% :by weight of a polymer of a methacrylate ester containing from 8 to 18 carbon atoms in the ester portion thereof, from about 0.8% to 2.0% by weight of a detergent inhibitor selected from the class consisting of metal salts of sulfonic acids, and from about 0.01% to 5.0% by weight of a compatibility improved having the formula wherein R is an alkyl group containing from 1 [to 8 carbon atoms, R is a radical selected from the group consisting of hydrogen and alkyl groups containing from 1 to 8 carbon atoms, and n is an integer from 1 to 8.

10. A non-turbid lubricating oil blend which consists essentially of a mineral oil base stock having combined therein about 0.1 to about 2.0% by weight of a copolymer of a maleate ester containing from 8 to 18 carbon atoms in the ester portion thereof and a vinyl ester, from about 08% to 2.0% by weight of a detergent inhibitor selected from the class consisting of metal salts of sulfonic acids, and from about 0.05% to 4.0% by weight of a compatibility improver of the formula RO(CH CH O),,R' wherein R is an alkyl group containing from 1 to 8 carbon atoms, R is a radical selected from the group consisting of hydrogen and alkyl groups containing from 1 to 8 carbon atoms, and n is an integer from 1 to 8.

References Cited in the file of this patent UNITED STATES PATENTS 2,383,915 Morgan Aug. 28, 1945 2,602,048 Michaels et a1. July 1, 1952 2,616,851 Giammaria Nov. 4, 1952 

1. A NON-TURBID LUBRICATING OIL BLEND WHICH CONSISTS ESSENTIALLY OF A MINERAL OIL BASE STOCK HAVING COMBINED THEREIN ABOUT 0.05% TO ABOUT 10% BY WEIGHT OF A VISCOSITY INDEX IMPROVING MATERIAL SELECTED FROM THE CLASS CONSISTING OF POLYMERIZED ALPHA, BETA-UNSATURATED CARBOXYLIC ACID ESTERS CONTAINING FROM ABOUT 8 TO ABOUT 18 CARBON ATOMS IN THE ESTER PORTION THEREOF AND COPOLYMERS OF SUCH ESTERS WITH VINYL ESTERS, FROM ABOUT 0.2% TO 3.0% BY WEIGHT OF A DETERGENT INHIBITOR SELECTED FROM THE CLASS CONSISTING OF METALLIC SALTS OF SULFONIC ACIDS AND FROM 0.01% TO 5.0% OF A MATERIAL HAVING THE FORMULA 